Blood pressure measurement is generally referred to as sphygmomanometry. Segmental sphygmomanometry is measurement of blood pressures at different portions, or segments, of a patient's body. Often, bilateral vascular measurements are taken along symmetrical segments of a patient's body, for instance, left and right ankles, and left and right forearms. Segmental sphygmomanometry allows comparisons of blood pressures between segments and between symmetrically paired locations, which can provide information as to conditions of corresponding blood vessels. Peripheral arterial disease (PAD) is a condition where fatty deposits (or plaque) collect along walls of blood-carrying arteries. PAD is also known as atherosclerosis or the hardening of arteries. PAD is associated with a high risk of both fatal and nonfatal ischemic events, such as myocardial infarction (MI), stroke, and other thromboembolic events. However, once detected, plaque buildup associated with PAD can often be stopped or reduced.
One important and well-known blood pressure indicator is the ankle-brachial index (ABI). The ABI provides a ratio of a systolic blood pressure in a patient's ankle divided by a systolic blood pressure in the patient's arm. ABI readings that fall outside of a normal range (e.g., outside about 0.91 to about 1.30) and asymmetrical bilateral ABI readings (e.g., ABI readings that differ significantly between left and right limbs) are indicators that assist in diagnosis of PAD.
Segmental sphygmomanometry can be conducted at a vascular lab using non-invasive testing equipment. However, many patients do not undergo regular vascular testing. Moreover, PAD is generally under-diagnosed. Yet it is desirable to diagnose PAD prior to an ischemic event. More robust diagnoses of PAD are possible with the aid of segmental blood pressure testing in a primary care environment. Primary care is basic or general care usually given by doctors who work with general and family medicine, internal medicine (internists), pregnant women (obstetricians), and children (pediatricians). In addition, a nurse practitioner (NP), a State licensed registered nurse with special training, can also provide this basic level of health care. A substantial obstacle to providing segmental blood pressure testing in the primary care environment is the complexity of testing procedures and testing equipment.
Known segmental blood pressure testing equipment can include multiple pressure cuffs and multiple flow sensors, all of which require proper connection to testing control equipment and proper positioning relative to a patient's body. Generally, a segmental testing procedure is conducted as follows. A number of blood pressure cuffs are simultaneously placed on the extremities on which the pressure measurements are to be performed. Three locations are typically included: arm, ankle and toe. A flow sensor, such as a Doppler flow sensor, is placed over a desired artery distal to the inflated cuff. Then, in order to obtain a pressure measurement at a cuff, the cuff is inflated to a pressure higher than the patient's systolic blood pressure. The precise pressure level to which a cuff is inflated is determined by medical personnel (i.e., the primary care provider) operating the testing equipment. Inflation of a cuff temporarily halts blood flow at that cuff. Then the pressure in the cuff is gradually lowered by medical personnel, and a pressure reading is taken at the appearance of a distal blood flow (i.e., a return of blood flow), which is detectable with the flow sensor as a point of apparition of a pulsating waveform generated on a display screen of the testing equipment or as an audible nock.
Improper use of segmental blood pressure testing equipment due to inadequate training and incorrect technique can undermine diagnostic utility of the testing procedure. For instance, the flow sensor must be properly positioned relative to vasculature to obtain accurate results. Primary care providers can be overburdened by the use of complex segmental blood pressure testing equipment. Mover, documentation of vascular data is subjective, because operators select return of flow pressures based upon the appearance of an audible nock or by waveform interpretation. This presents an obstacle to obtaining accurate vascular test data in the primary care environment. Complexity and variability of prior art systems prevents primary care providers from integrating diagnostic procedure and practice, thereby inhibiting disease detection.
Diagnoses of cardiovascular conditions may require interpretation of vascular test data by a specialist. Vascular testing conducted in a primary care environment may require interpretation by a physician qualified in an appropriate specialty who is in a location physically remote from the primary care environment. Intercommunication of test data and test interpretation becomes important in providing quick diagnoses.
It is therefore desired to provide a vascular sensing system that is sufficiently easy to use in a primary care environment, so that primary care providers, such as technologists and primary care physicians, can reliably and accurately perform testing and acquire cardiovascular data. It is further desired to provide vascular test data to a qualified interpreting physician, who may be at a location remote from the primary care environment, thereby facilitating a diagnosis by a physician qualified in an appropriate specialty.
Thus, a reliable and accurate vascular testing system is needed that easily permits non-invasive measurement of vascular pressure characteristics in a primary care environment for assisting diagnosis of vascular conditions.